The proposed investigation will study the relationships between conformational fluctuations and segmental mobility of hemoglobin and its allosteric transitions as seen in the overall liganded-to-unliganded conformational change and in the conformation of the intermediate of ligation of the system. Conformation fluctuations and segmental mobility will be approached using nanosecond fluorimetry and fluorescence deplorization techniques. The intermediates of ligation will be approached by measuring the sedimentation equilibrium of partially ligated solution of hemoglobin. Mutant and chemically modified hemoglobins will be used in order to test the effect of specific amino acid substitutions on the conformational dynamic of the system and in order to have better access to the characteristics of the intermediates of ligation of the protein.